A tire air pressure detection device in the related art described in Patent Document 1 includes a transmitter which is provided with a pressure sensor and attached to an air injection valve in a wheel rim of each wheel, and detects a tire air pressure by transmitting data on a tire air pressure from the transmitter to a receiver on a vehicle body side. In the tire air pressure detection device as above, the transmitter is installed inside a tire and power cannot be supplied to the transmitter from an in-vehicle battery. Accordingly, a battery is equipped to the transmitter and the transmitter detects a tire air pressure and transmits data on power supplied from the battery.
As has been described, because the tire air pressure detection device in the related art drives the transmitter on power supplied from the battery, a reduction of power consumption is an issue to be addressed. In an effort to reduce power consumption, data is transmitted from the transmitter after a vehicle starts running, and whether the vehicle starts running is detected depending on whether a measured value of an acceleration sensor is large or small. It is, however, difficult to accurately detect that the vehicle starts running unless a vehicle speed reaches or exceeds a certain speed (for example, 30 km/h) after a running start of the vehicle because of accuracy of the acceleration sensor, and it takes a time to output tire air pressure information in some cases. That is to say, in a case where the transmitter is provided to the air injection valve in the wheel rim, only acceleration by rotation of the wheel is available to detect whether vehicle starts running and whether the vehicle starts running cannot be detected accurately unless a vehicle speed reaches a certain speed.